The following is a tabulation of some prior art that may be relevant:
U.S. PatentsKindPat. No.CodeIssue DatePatentee or Assignee8,080,901B2Dec. 20, 2011Loganathan Doraisamy7,112,746B2Sep. 26, 2006Nobuhiko Tsukahara et al.4,521,767Jun. 4, 1985 Richard F. Bridge3,911,390Oct. 7, 1975Richard H. MeyersU.S. Patent Application PublicationsKindPub. No.Code Pub. DateApplicant2014/0020815A1Jan. 23, 2014Paul R. Dickinson et al.2002/0038716A1Apr. 4, 2002Ronald Anthony PinedaForeign Patent DocumentsForeign Doc.CountryKindNo.CodeCodePub Date.Patentee9935346WOA1Jul. 15, 1999Helideo Costa-Elias et al.2762155FRA1Oct. 16, 1998Giebel Wolfganget al.2002131024JPMay 9, 2002Ryoji Kobayashiet al.7318741JPADec. 8, 1995Yamada Taro
Some of the prior art above has low relevance to this application. Doraisamy Loganathan (2011) addresses electrical power generation from a road surface. Richard F. Bridge (1985) deals with using a fiber link in a security trip wire system. Richard H. Myers (1975) speaks of a road traffic monitoring system. Ryoji Kobayashi et al. (2002) has an overhead projector application. Yamada Taro (1995) presents a cable/connector assembly.
The remaining prior art for installing fiber optic cable may be divided into two categories. One category, illustrated by Nobuhiko Tsukahara et al. (2006) and by Dickinson et al. (2014), addresses the installation of fiber on or inside a building but does not provide a capability for fiber installation over any appreciable distance. Nobuhiko Tsukahara et al. (2006) and Dickinson et al. (2014) also do not protect the fiber on the ground from vehicle or foot traffic. The second category of prior art does reference a capability for installation of communication lines over an appreciable distance and will be addressed below.
The usual process for manufacturing a communications cable for distance installation varies widely but usually consists of extruding plastic core tubes around fibers, helically wrapping the tubes around a central strength member, building up several layers of protective sheathing, surrounding the sheathing with armor such as steel and surrounding the armor with a heavy polymer jacket.
Once a cable is manufactured, it can be pulled through conduits, hung along telephone poles, buried inside trenches as per Giebel Wolfgang et al. (1998), installed using a horizontal directional drill, micro-trenched into a roadway as per Helideo Costa-Elias et al. (1999), or installed on a roadway by using a flat fiber conduit for further protection, as per Ronald Anthony Pineda (2002).
The use of armor and other materials increases the weight, fabrication cost, and installation footprint of the fiber cable. The larger installation footprint often requires the significant disruption and repair of the installed route, all of which contributes to higher installation cost.
When installing below the surface, fiber cables can either be direct -buried or installed into a conduit to further protect the cable. Conduit is often installed by trenching into the ground or using a horizontal directional drill to install conduit over short distances without disrupting the surface. The use of conduit requires the added cost and overhead of conduit installation along with the fiber cable manufacturing and installation.
Aerial installs are performed by draping communication cables on communication or power distribution poles. Although this can provide for a quicker install than trenching or micro-trenching, it has several downsides. If the poles do exist, they could already be holding the maximum weight allowed, rendering them useless for expansion. Additionally, trees, buildings, personal property, and other utilities, often interfere with the installation of new poles or cables. Installers are endangered by nearby local traffic, the height at which they must work, and the often dangerous voltages in the vicinity of their work area. Overhead installations are affected by unavoidable weather conditions, such as ice storms and thunderstorms. These environmental conditions often damage overhead installations for extended periods of time and require expensive repairs. Additionally, aerial installations are not aesthetically pleasing, compared to other lower visibility installation techniques.
Plowing, direct burial or other similar installs email an array of machines that utilize a cutting blade to trench through soil or other natural ground substances. The communication cable is installed in a single-pass process, first by cutting the trench, burying the cable, and then backfilling the trench with a filler material suitable for the ground surface. This installation technique as per Giebel Wolfgang et al. (1998) causes significant disruption to local roadway infrastructure with attendant business impacts and transportation delays.
Horizontal directional drilling is a method of installing fiber optic cables underground without having to disrupt local surface features. This is typically done to install cables under surface obstacles that cannot be avoided by route planning such as rivers, roads, and buildings. There is risk of damaging other underground infrastructure as the drilling bit bores through the ground This method is equipment and labor intensive, and is more of an obstacle avoidance technique than a complete end to end communication cable installation technique.
A micro-trenching install is similar to a trenching or plowing install, but the cutting tool and ground opening are smaller, and the filler materials required are typically less than trenching. The micro-trenching install is mainly used on roadways and utilizes a heavy duty diamond saw blade that cuts a narrow, perhaps inches wide, section of a roadway or similar surface to a predetermined depth dependent on the location. A communication cable is installed or micro duct is inserted for later filling with a communication cable. After that, the micro-trench is backfilled with an aggregate and other approved materials. The risks of this technique as per Helideo Costa-Elias et al. (1999) include cutting of an existing utility, the infliction of damage to the integrity of the road surface requiring significant repair, and many of the same risks to installers as the roadside aerial installation. Additionally, micro-trenching is not preferred in situations that involve private roads, shallow road surfaces, bridges, and tunnels, to name a few.
The use of traffic resistant conduit, as per Ronald Anthony Pineda (2002), installed directly on a roadway entails the added cost of fabricating and installing the conduit.
Prior art communication line installations limitations include: a limited ability to economically provide rural and some suburban service on an individual customer basis, a limited ability to reach rural and suburban customers on an economical basis, installation times that often range from weeks to months to years, installation methods that usually entail significant business impacts due to traffic disruption along with increased labor, time, and costs, and often an inherently higher risk of injury to installers (i.e. trench collapse, traffic accidents, heavy equipment risks, accidental damage to other utilities, and high voltage electric shock for installers).